Method and apparatus for handling a cell change

ABSTRACT

Example embodiments presented herein are directed towards a user equipment, and corresponding methods therein, for handling a cell change from a first cell to a second cell in a wireless communications network. Some example embodiments may also be directed towards the user equipment altering a duration of a measurement time over which at least one measurement is performed, and altering a measurement bandwidth of the at least one measurement. The alterations may be performed based on associated bandwidths of the first and second cells. Other example embodiments may be directed towards a network node, and corresponding method therein, for sending, to the user equipment, a notification of a cell change and information associated with the cell change. Example embodiments may further comprise the network node receiving measurement data of at least one measurement performed over an altered measurement bandwidth and an altered duration of measurement time, where the alterations are based on the information associated with the cell change.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/848,693, filed on Sep. 9, 2015, (now U.S. Pat. No. 9,432,905, issuedon Aug. 30, 2016), which is a continuation of U.S. patent applicationSer. No. 13/503,646, filed on Apr. 23, 2012, (now U.S. Pat. No.9,173,150, issued on Oct. 27, 2015), which is a National Stage Entry ofInternational Application No. PCT/SE2012/050351, filed on Mar. 29, 2012(now International Publication No. WO 2012/177205, publication date Dec.27, 2012), which is related to, and claims priority from, U.S.Provisional Patent Application No. 61/499,689, filed on Jun. 21, 2011,the disclosure of all of these applications being expressly incorporatedhere by reference.

TECHNICAL FIELD

Example embodiments presented herein are directed towards a userequipment, and corresponding method therein, for handling a cell change.Example embodiments presented herein are also directed towards a networknode, and corresponding method therein, for handling a cell change of auser equipment.

BACKGROUND Overview of Wireless Communications Networks

In a typical cellular system, also referred to as a wirelesscommunications network, wireless terminals, also known as mobilestations or user equipments, communicate via a Radio Access Network(RAN) to one or more core networks. The wireless terminals can be mobilestations or user equipment units such as mobile telephones also known as“cellular” telephones, and laptops with wireless capability, e.g.,mobile termination, and thus can be, for example, portable, pocket,hand-held, computer-comprised, or car-mounted mobile devices whichcommunicate voice and/or data with radio access network.

The radio access network covers a geographical area which is dividedinto cell areas, with each cell area being served by a base station,e.g., a Radio Base Station (RBS), which in some networks is also called“eNodeB” or “NodeB” and which in this document also is referred to as abase station. A cell is a geographical area where radio coverage isprovided by the radio base station equipment installed at a base stationsite. Each cell is identified by an identity within the local radioarea, which is broadcast in the cell. The base stations communicate overthe air interface operating on radio frequencies with the user equipmentunits within range of the base stations.

In some versions of the radio access network, several base stations aretypically connected, e.g., by landlines or microwave, to a Radio NetworkController (RNC). The radio network controller, also sometimes termed aBase Station Controller (BSC), supervises and coordinates variousactivities of the plural base stations connected thereto. The radionetwork controllers are typically connected to one or more corenetworks. In some networks, there is also an interface between radionodes, e.g., the X2 interface between eNodeBs in LTE.

The Universal Mobile Telecommunications System (UMTS) is a thirdgeneration mobile communication system, which evolved from the GlobalSystem for Mobile Communications (GSM), and is intended to provideimproved mobile communication services based on Wideband Code DivisionMultiple Access (WCDMA) access technology. UMTS Terrestrial Radio AccessNetwork (UTRAN) is essentially a radio access network using widebandcode division multiple access for user equipment units. The ThirdGeneration Partnership Project (3GPP) has undertaken to evolve furtherthe UTRAN and GSM based radio access network technologies. Long TermEvolution (LTE) together with Evolved Packet Core (EPC) is the newestaddition to the 3GPP family.

Radio measurements play a key role in wireless communications. At ageneral level, radio measurements may be categorized into signalstrength/quality measurements, timing measurements, and othermeasurements. The measurements may be performed by the user equipmentand/or radio network nodes equipped with a radio interface. Thedifferent categories or radio measurements, and other network aspectsrelated to radio measurements, are described in greater detail belowaccording to the provided sub-headings.

Signal Strength and Quality Measurements

Examples of LTE measurements characterizing signal strength or qualityof a given cell are Reference Signal Received Power (RSRP), ReferenceSignal Received Quality (RSRQ), received interference power, and thermalnoise power. RSRP and RSRQ are currently defined as user equipmentmeasurements, e.g., in DL, and associated with cell-specific referencesignals (CRS). However, received signal strength and received signalquality measurements are known to be more general, e.g., for any type ofsignal and for DL and UL. Similar measurements exist in UMTS, GSM andCDMA2000, etc.

Timing Measurements

In LTE, the following user equipment timing measurements have beenstandardized since release 9, user equipment Rx-Tx time difference,Reference Signal Time Difference (RSTD), and user equipment GNSS Timingof Cell Frames for user equipment positioning. The following E-UTRANmeasurements have been standardized since release 9, eNodeB Rx-Tx timedifference, Timing Advance (TA), TA Type 1=(eNB Rx-Tx timedifference)+(user equipment Rx-Tx time difference), TA Type 2=(eNB Rx-Txtime difference), and E-UTRAN GNSS Timing of Cell Frames for userequipment positioning.

In addition, there may also be measurements that are not explicitlystandardized, but may still be implemented by user equipment or E-UTRANor standardized later. Some examples of these measurements may be timeof arrival, measured by radio node, e.g., eNodeB or a radio measurementnode such as LMU, RSTD measured by radio nodes, one way propagationdelay, measured by eNode B for estimation of timing advanced to besignaled to the user equipment (a similar user equipment measurement maybe defined in the future), and timing measurements over multifariouslinks. Similar measurements may also exist in other RATs, e.g., Rx-Txmeasurements may be similar to Round Trip Time (RTT) measurements inUMTS, and RSTD may be similar to a System Frame Number (SFN)-to-SFN timedifference in UMTS.

Timing measurements may be used for positioning (e.g., with EnhancedCell Identification (E-CID), Adaptive Enhanced Cell ID (AECID), patternmatching, Observed Time Difference of Arrival (OTDOA), Uplink TimeDifference of Arrival (U-TDOA), hybrid positioning methods),Minimization of Drive Tests (MDT), network planning,Self-Optimizing/Organizing Network (SON), enhanced inter-cell resourceand interference coordination (eICIC) and heterogeneous network (HetNet)(e.g., for optimizing the cell ranges of different cell types),configuration of handover parameters, time-coordinated scheduling, etc.Measurements of a general purpose are typically configured by theserving/primary cell. Measurements of a specific purpose may beconfigured by other nodes, e.g., by positioning node (e.g., EvolvedServing Mobile Location Centre (E-SMLC) or Secure User Plane LocationPlatform (SLP) in LTE), SON node, MDT node, etc.

Timing advance may also be used to control the timing adjustment of userequipment UL transmissions. The adjustment is transmitted to the UE inthe timing advance command. In LTE, for user equipments not supportingLPP, the user equipment timing adjustment may be based on TA Type 2.

User equipment measurements configured by the network are typicallyreported to a network node, e.g., eNodeB, positioning node, etc. Radionode measurements may also be reported to a network node, e.g., anotherradio node such as eNodeB or LMU, or other network node such aspositioning node. Some measurements may be not reported but usedinternally by the measuring node, including the user equipment.Furthermore, some measurements may involve both directions (DL and UL),e.g., Rx-Tx measurements. It should also be appreciated that the userequipment may also be involved in the radio node (e.g., eNodeB)measurements such as Rx-Tx measurements, and eNodeB may also be involvedin the user equipment measurements such as Rx-Tx measurement.

Other Measurements

An example of a measurement that does not belong to the first two groupsof measurements is an Angle of Arrival (AoA) measurement. In the currentLTE standard, AoA is defined as an E-UTRAN measurement. However, AoAmeasurements performed by the user equipment are also known.

Inter-Frequency, Inter-Band, and Inter-RAT Measurements

User equipments typically support all intra-RAT measurements (i.e.inter-frequency and intra-band measurements) and meet the associatedrequirements. However the inter-band and inter-RAT measurements are userequipment capabilities, which are reported to the network during thecall setup. The user equipment supporting certain inter-RAT measurementsshould meet the corresponding requirements. For example a user equipmentsupporting LTE and WCDMA should support intra-LTE measurements,intra-WCDMA measurements and inter-RAT measurements (i.e. measuringWCDMA when serving cell is LTE and measuring LTE when serving cell isWCDMA). Hence, the network can use these capabilities according to itsstrategy. These capabilities are highly driven by factors such as marketdemand, cost, typical network deployment scenarios, frequencyallocation, etc.

Inter-Frequency Measurements

Inter-frequency measurements involve measurements on at least one cell(e.g., RSTD measurement involves two cells) that belong to afrequency/carrier different from the serving/primary cellfrequency/carrier. Examples of inter-frequency measurements areinter-frequency RSRP, inter-frequency RSRQ, inter-frequency RSTD, etc.

The user equipment performs inter-frequency and inter-RAT measurementsin measurement gaps. The measurements may be done for various purposes:mobility, positioning, self organizing network (SON), minimization ofdrive tests, etc. Furthermore, the same gap pattern is used for alltypes of inter-frequency and inter-RAT measurements. Therefore E-UTRANmust provide a single measurement gap pattern with constant gap durationfor concurrent monitoring (i.e. cell detection and measurements) of allfrequency layers and RATs.

Inter-RAT Measurements

In general, in LTE inter-RAT measurements are typically defined similarto inter-frequency measurements, e.g. they may also require configuringmeasurement gaps like for inter-frequency measurements, but just withmore measurements restrictions and often more relaxed requirements forinter-RAT measurements. As a special example, there may also be multiplenetworks using the overlapping sets of RATs. The examples of inter-RATmeasurements specified currently for LTE are UTRA FDD CPICH RSCP, UTRAFDD carrier RSSI, UTRA FDD CPICH Ec/No, GSM carrier RSSI, and CDMA20001×RTT Pilot Strength. LTE FDD and TDD may also be treated as differentRATs.

Inter-Band Measurements

An inter-band measurement refers to the measurement done by the userequipment on a target cell on the carrier frequency belonging to thefrequency band which is different than that of the serving/primary cell.Both inter-frequency and inter-RAT measurements can be intra-band orinter-band.

The motivation for inter-band measurements is that most of the userequipments today support multiple bands even for the same technology.This is driven by the interest from service providers; a single serviceprovider may own carriers in different bands and would like to makeefficient use of carriers by performing load balancing on differentcarriers. A well-known example is that of multi-band GSM terminal with800/900/1800/1900 bands.

Furthermore, a user equipment may also support multiple technologiese.g. GSM, UTRA FDD and E-UTRAN FDD. Since all UTRA and E-UTRA bands arecommon, therefore the multi-RAT user equipment may support same bandsfor all the supported RATs.

Carrier Aggregation (CA) Networks

A multi-carrier system (or interchangeably called as the carrieraggregation (CA)) allows the user equipment to simultaneously receiveand/or transmit data over more than one carrier frequency. Each carrierfrequency is often referred to as a component carrier (CC) or simply aserving cell in the serving sector, more specifically a primary servingcell or secondary serving cell. The multi-carrier concept is used inboth HSPA and LTE. Carrier aggregation is supported for both contiguousand non-contiguous component carriers, and component carriersoriginating from the same eNodeB need not to provide the same coverage.Furthermore, carriers may also belong to different RATs. Belowdefinitions are provided for various cells in a CA network.

Serving Cell:

for a user equipment in RRC_CONNECTED not configured with CA there maybe only one serving cell comprising the primary cell. For a userequipment in RRC_CONNECTED configured with CA, the term ‘serving cells’is used to denote the set of one or more cells comprising of the primarycell and all secondary cells.

Primary Cell (PCell):

the cell, operating on the primary frequency, in which the userequipment either performs the initial connection establishment procedureor initiates the connection re-establishment procedure, or the cellindicated as the primary cell in the handover procedure.

Secondary Cell (SCell):

a cell, operating on a secondary frequency, which may be configured oncean RRC connection is established and which may be used to provideadditional radio resources.

In the downlink, the carrier corresponding to the PCell is the DownlinkPrimary Component Carrier (DL PCC) while in the uplink it is the UplinkPrimary Component Carrier (UL PCC). Depending on user equipmentcapabilities, Secondary Cells (SCells) can be configured to formtogether with the PCell a set of serving cells. In the downlink, thecarrier corresponding to a SCell is a Downlink Secondary ComponentCarrier (DL SCC) while in the uplink it is an Uplink Secondary ComponentCarrier (UL SCC).

In CA the base station (e.g. eNode B) in LTE can deactivate one or moresecondary cells on the corresponding secondary carriers. Thedeactivation is done by the eNode Busing lower layer signaling (e.g.over PDCCH in LTE) using a short command such as ON/OFF (e.g. using 1bit for each SCell). The activation/deactivation command is sent to theuser equipment via the PCell. Typically the deactivation is done whenthere is no data to transmit on the SCell(s). Theactivation/deactivation can be done independently on uplink and downlinkSCell. The purpose of the deactivation is thus to enable user equipmentbattery saving. The deactivated SCell(s) can be activated also by thesame lower layer signaling.

Cell Change in LTE

Herein, a cell change is referred to as changing the cell to which theuser equipment is associated to. The cell change may further refer, forexample, to:

-   -   serving cell change (e.g., at handover in a non-CA system or        when the user equipment is not configured with any SCell),    -   serving cell set change (e.g., in a CA system        adding/removing/modifying an SCell),    -   PCell change (e.g., in a CA system changing the current PCell        being cell with the first cell identity to another cell with the        second cell identity).

A cell change may occur, for example, during:

-   -   Handover (intra-frequency, inter-frequency or inter-RAT), or    -   PCell change on the same PCC (in a CA system), or    -   Carrier switching (changing the current PCC to another frequency        carrier, which implies also PCell change).

A cell change may be due to e.g. mobility, load balancing, energysaving, carrier activation/deactivation or cell activation/deactivation,secondary carrier activation/deactivation or secondary cell (orsecondary serving cell) activation/deactivation, etc.

Measurement Requirements at a Cell Change

Most of the measurements characterize a signal of a specific cell, e.g.,a serving or a neighbor cell. Some of the measurements relate to signalsof two specific cells, e.g., relative measurements such as RSTD betweena neighbor and a reference cell. A few measurements characterize theradio environment at a specific location (e.g., interference- andnoise-related measurements such as Thermal noise power, ReceivedInterference Power, RSSI or Noise Rise).

A measurement may be specified for a certain cell (e.g., identified bythe cell identity) or a certain cell category (e.g., a serving cell,reference cell, neighbor cell). The cell identification of the same celldoes not change when e.g. the serving cell change occurs for a userequipment. However, the category of a cell may or may not change whenthe user equipment is moving from one cell to another cell, e.g., theserving cell changes during handover or carrier switching, but OTDOAreference cell may not change. Therefore, the measurements associatedwith a certain cell (e.g., like in OTDOA) may in principle continueafter, e.g., handover, whilst the measurement associated with a certaincell category may need to be stopped or restarted at handover, dependingon the measurement and cell category.

Example 1: Requirements for User Equipment Rx-Tx Measurements forPositioning when Handover Occurs

The current standard specifies that if the user equipment is performinguser equipment Rx-Tx time difference measurement while the serving cellis changed due to the handover then the user equipment shall restart theRx-Tx measurement on the new cell. In this case the user equipment shallalso meet the user equipment Rx-Tx time difference measurement andaccuracy requirements. However the physical layer measurement period ofthe user equipment Rx-Tx measurement shall not exceed T_(measure) _(_)_(FDD) _(_) _(UE) _(_) _(Rx) _(_) _(Tx3) as defined in the followingexpression: T_(measure) _(_) _(FDD) _(_) _(UE) _(_) _(Rx) _(_)_(Tx3)=(K+1)*(T_(measure) _(_) _(FDD) _(_) _(UE) _(_) _(Rx) _(_) _(Tx1))K*T_(PCell) _(_) _(change) _(_) _(handover), where K is the number oftimes the serving cell is changed over the measurement period(T_(measure) _(_) _(FDD) _(_) _(UE) _(_) _(Rx) _(_) _(Tx3)), T_(PCell)_(_) _(change) _(handover) is the time to change the serving cell due tohandover; it can be up to 45 ms.

Example 2: Requirements for User Equipment Rx-Tx Measurements forPositioning when PCell Switching Occurs with Carrier Aggregation

If the user equipment supporting E-UTRA carrier aggregation whenconfigured with the secondary component carrier is performing userequipment Rx-Tx time difference measurement while the PCell is changedregardless whether the primary component carrier is changed or not thenthe user equipment shall restart the Rx-Tx measurement on the new PCell.In this case the user equipment shall also meet the user equipment Rx-Txtime difference measurement and accuracy requirements. However thephysical layer measurement period of the user equipment Rx-Txmeasurement shall not exceed T_(measure) _(_) _(FDD) _(_) _(UE) _(_)_(Rx) _(_) _(Tx2) as defined in the following expression: T_(measure)_(_) _(FDD) _(_) _(UE) _(_) _(Rx) _(_) _(Tx2)=(N+1)*(T_(measure) _(_)_(FDD) _(_) _(UE) _(_) _(Rx) _(_) _(Tx1))+N*T_(Pcell) _(_) _(change)_(_) _(CA), where: N is the number of times the PCell is changed overthe measurement period (T_(measure) _(_) _(FDD) _(_) _(UE) _(_) _(Rx)_(_) _(Tx2))₇ T_(Pcell) _(_) _(change) _(_) _(CA) is the time to changethe PCell; it can be up to 25 ms.

For OTDOA, the user equipment performs RSTD measurements with respect tothe reference cell, so in general the user equipment should be able tocontinue the RSTD measurements after the serving/primary cell changeswhen the assistance data is provided with respect to a reference cellwhich is not restricted to be the serving cell.

Impact of RF Receiver Reconfiguration on Measurement

In single carrier LTE, the cell may operate at the channel bandwidthsranging from 1.4 MHz to 20 MHz. However, single-carrier legacy userequipment shall be able to receive and transmit over 20 MHz, i.e., themaximum single-carrier LTE bandwidth. If the serving cell bandwidth issmaller than 20 MHz, then the user equipment may also shorten thebandwidth of its RF front end. For example, if the serving cellbandwidth (BW) is 5 MHz, then the user equipment may also configure itsRF BW to 5 MHz. This approach has several advantages. For example itenables the user equipment:

-   -   To prevent the user equipment from the noise outside the current        reception bandwidth,    -   To save its battery life by lowering the power consumption.

The reconfiguration of the user equipment reception and/or transmissionbandwidth involves some delay, e.g., 0.5-2 ms or longer, depending uponuser equipment implementation and also whether both UL BW and DL BW arereconfigured at the same time or not. This small delay is often referredto as a ‘glitch’. During the glitch the user equipment cannot receivefrom the serving cell or transmit to the serving cell. Hence this maylead to interruption in data reception/transmission from/to servingcell. The user equipment is also unable to perform any type ofmeasurements during the glitch. The glitch occurs either when the userequipment extends its bandwidth (e.g. from 5 MHz to 10 MHz) or when itshortens its bandwidth (e.g. from 10 MHz to 5 MHz).

Furthermore, when the user equipment operates at a bandwidth lower thanits maximum reception capability and the user equipment wants to measureover a larger than the current bandwidth, e.g., for measuring a cell onthe same frequency, then it has to open its receiver for performing themeasurement. Thus, in this case (i.e. when current BW<max BW) the glitchoccurs before and after the user equipment obtains each measurementsample, if the user equipment reconfigures back to its current operationafter each measurement sample over the larger bandwidth. On the otherhand, keeping the receiver open, e.g. up to max bandwidth, to enable ameasurement of a larger-bandwidth neighbor cell on the same frequencywithout a glitch when the system bandwidth of a first measured cell issmaller than max BW would lead to performance degradation of the firstcell measurements.

The glitch also occurs when the CA capable user equipment reconfiguresits bandwidth from single carrier to multiple carrier mode or viceversa, or when activating/deactivating CA cells or component carriers.For example, consider CA capable user equipment supporting 2 DLcomponent carriers each of 20 MHz: PCC and 1 SCC. If the secondarycomponent carrier is deactivated by the serving/primary cell then theuser equipment will shorten its BW e.g. from 40 MHz to 20 MHz. This maycause 1-2 ms or even longer interruption on the PCC.

Positioning Architecture in LTE

The three key network elements in an LTE positioning architecture arethe LCS Client, the LCS target and the LCS Server. The LCS Server is aphysical or logical entity managing positioning for a LCS target device(typically a user equipment or a radio node) by collecting measurementsand other location information, assisting the terminal in measurementswhen necessary, and estimating the LCS target location. A LCS Client isa software and/or hardware entity that interacts with a LCS Server forthe purpose of obtaining location information for one or more LCStargets, i.e. the entities being positioned. LCS Clients may reside in anetwork node, radio network node, a user equipment, and it may alsoreside in the LCS targets themselves. An LCS Client sends a request toLCS Server to obtain location information, and LCS Server processes andserves the received requests and sends the positioning result andoptionally a velocity estimate to the LCS Client. A positioning requestcan be originated from the terminal, radio network or the network.

Position calculation can be conducted, for example, by a positioningserver (e.g. E-SMLC or SLP in LTE) or UE. The former approachcorresponds to the user equipment-assisted positioning mode, whilst thelatter corresponds to the user equipment-based positioning mode.

Two positioning protocols operating via the radio network exist in LTE,LPP and LPPa. The LPP is a point-to-point protocol between a LCS Serverand a LCS target device, used in order to position the target device.LPP can be used both in the user and control plane, and multiple LPPprocedures are allowed in series and/or in parallel thereby reducinglatency. LPPa is a protocol between eNodeB and LCS Server specified onlyfor control-plane positioning procedures, although it still can assistuser-plane positioning by querying eNodeBs for information and eNodeBmeasurements. SUPL protocol is used as a transport for LPP in the userplane. LPP has also a possibility to convey LPP extension messagesinside LPP messages, e.g. currently OMA LPP extensions are beingspecified (LPPa) to allow e.g. for operator-specific assistance data orassistance data that cannot be provided with LPP or to support otherposition reporting formats or new positioning methods.

A high-level architecture, as it is currently standardized in LTE, isillustrated in FIG. 1, where the LCS target is a terminal, and the LCSServer is an E-SMLC or an SLP. In the figure, the control planepositioning protocols with E-SMLC as the terminating point are shown inblue, and the user plane positioning protocol is shown in red. SLP maycomprise two components, SPC and SLC, which may also reside in differentnodes. In an example implementation, SPC has a proprietary interfacewith E-SMLC, and Llp interface with SLC, and the SLC part of SLPcommunicates with P-GW (PDN-Gateway) and External LCS Client.

Additional positioning architecture elements may also be deployed tofurther enhance performance of specific positioning methods. Forexample, deploying radio beacons is a cost-efficient solution which maysignificantly improve positioning performance indoors and also outdoorsby allowing more accurate positioning, for example, with proximitylocation techniques.

SUMMARY

During operations, a user equipment may often change from one cell toanother, referred to as a cell change operation. During a mobilityprocedure, resulting in a cell change, positioning measurementsperformed by a user equipment may be interrupted or negatively affected.Thus, at least one object of some of the example embodiments presentedherein is to provide a way of handling such cell changes to minimize orreduce interruptions on measurements caused by the cell change.

Thus, example embodiments presented herein are directed towards improvedpositioning measurements during a user equipment cell change. Some ofthe example embodiments presented herein may be generally summarized asfollows:

-   -   Enabling the network node (e.g., eNode B, MDT, SON, positioning        node, etc) to obtain user equipment cell changing information        (e.g. list of serving/primary cells, additional user equipment        trajectory information etc) over certain time period.    -   Configuration of a node with specific measurements while        accounting for cell change of the user equipment.    -   The user equipment performing configured measurements while        accounting for cell change.    -   The obtained user equipment cell change information being used        by the network node for one or more task associated with the        monitoring, management and/or planning of the network,        positioning, tracking, etc.    -   Pre-defined rules on user equipment behavior to ensure user        equipment meets positioning measurement requirements during cell        change (i.e. when the serving cell/PCell changes) over the        positioning measurement period while taking into account at        least the bandwidth of all the serving cell(s)/PCell(s).

Accordingly, some of the example embodiments presented herein may bedirected towards a method in a user equipment for handling a cellchange, where the user equipment is comprised in a wirelesscommunications network. The method comprises performing at least onemeasurement and receiving, from a network node, a notification of, andinformation associated with, a cell change from a first cell to a secondcell. The method also comprises performing the cell change during the atleast one measurement and altering a duration of a measurement time overwhich the at least one measurement is performed. The method furthercomprises altering a measurement bandwidth of the at least onemeasurement, wherein the altering is based on the associated bandwidthsof the first and a second cells. The method also comprises completingthe at least one measurement based on the altered duration ofmeasurement time and the altered measurement bandwidth.

Some example embodiments may be directed towards a user equipment forhandling a cell change, where the user equipment is comprised in awireless communications network, the user equipment comprises ameasurement unit configured to perform at least one measurement and areceiving port configured to receive, from a network node, anotification of, and information associated with, the cell change from afirst cell to a second cell. The measurement unit is further configuredto perform the cell change during the at least one measurement. The userequipment also comprises an alteration unit configured to alter aduration of a measurement time over which the at least one measurementis performed. The alteration unit is further configured to alter ameasurement bandwidth of the at least one measurement, wherein thealteration of the measurement time and the measured bandwidth is basedon associated bandwidths of the first and second cells. The measurementunit is further configured to complete the at least one measurementbased on the altered duration of measurement time and the alteredmeasurement bandwidth.

Some example embodiments are directed towards a method in a network nodefor handling a cell change of user equipment, where the network node iscomprised in a wireless communications network. The method comprisessending a request, to a user equipment, for performing at least onemeasurement and determining information associated with a cell changefrom a first cell to a second cell, where the information associatedwith the cell change comprises alteration instructions for altering auser equipment measurement time and measurement bandwidth in a presenceof the cell change. The method further comprises sending, to the userequipment, a notification of, and the information associated with, thecell change. The method further comprising receiving, from the userequipment, measurement data from a user equipment, the measurement datacomprising at least one other measurement performed over the alteredduration of measurement time and the altered measurement bandwidth,wherein the altered duration of measurement time and the alteredmeasurement bandwidth are based on bandwidths associated with the firstand the second cells.

Some example embodiments may be directed towards a network node forhandling a cell change of a user equipment, where the network node iscomprised in a wireless communications network. The network nodecomprises a transmitting port configured to transmit a request, to auser equipment, for performing at least one measurement and analteration unit configured to determine instructions for altering a userequipment measurement time and measurement bandwidth in a presence of acell change form a first cell to a second cell. The transmitting port isfurther configured to send, to the user equipment, a notification of,and information associated with, the cell change, said informationcomprising the instructions for altering. The network node alsocomprising a receiving port configured to receive, from the userequipment, measurement data, said measurement data comprising at leastone other measurement performed over an altered duration of measurementtime and an altered measurement bandwidth, wherein the altered durationof measurement time and the altered measurement bandwidth are based onthe transmitted instructions for altering and bandwidths associated withthe first and the second cells.

The example embodiments presented herein provide increased accuracy ofposition measuring in radio networks and enable maintaining thepositioning performance when a cell change occurs during a measurement.Furthermore, utilizing the example embodiments presented herein mayprovide for greater efficiency in the usage of network resources.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particulardescription of the example embodiments, as illustrated in theaccompanying drawings in which like reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe example embodiments.

FIG. 1 is a schematic of positioning architecture in LTE;

FIG. 2 is an illustrative example of user equipment performing apositioning measurement;

FIG. 3 is an illustrative example of a user equipment recordation,according to some of the example embodiments;

FIG. 4 is a schematic of a user equipment, according to some of theexample embodiments;

FIG. 5 is a schematic of a network node, according to some of theexample embodiments;

FIG. 6 is a flow diagram depicting example operations which may beperformed by the user equipment of FIG. 4; and

FIG. 7 is a flow diagram depicting example operations which may beperformed by the network node of FIG. 5.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particularcomponents, elements, techniques, etc. in order to provide a thoroughunderstanding of the example embodiments. However, the exampleembodiments may be practiced in other manners that depart from thesespecific details. In other instances, detailed descriptions ofwell-known methods and elements are omitted so as not to obscure thedescription of the example embodiments.

Overview of Positioning Measurements

For the purposes of explanation, an overview of positioning methods willbe provided. Thereafter, limitations of such methods will be identifiedand discussed. FIG. 1 illustrates positioning architecture in an LTEsystem. The positioning architecture may comprise a user equipment 101which may be configured to perform positioning measurements. The userequipment 101 may be in communication with a base station 103. The basestation 103 may be in communication with a core network comprising aServing Gateway (SGW) 109, a Packet Data Network Gateway (PGW) 111 and aMobility Management Entity (MME) 107. The core network may also compriseone or more nodes with positioning functionality, for example, a GatewayMobile Location Centre (GMLC) 105, an Enhanced Serving Mobile LocationCentre (E-SMLC) 115 and/or a Secure User Plane Location Platform (SLP)113.

The GMLC 105 may be used to request routing information from the HLR(Home Location register) or HSS (Home Subscriber Server). The GMLC 105may also be used to send positioning requests to either the VMSC(Visited Mobile Switching Centre), SGSN (Serving GPRS Support Node), MSC(Mobile Switching Centre) Server, or MME and receive final locationestimates from the corresponding entity. The E-SMLC 115 may communicatewith the user equipment 101 for location services and assistance datadelivery using an LPP protocol. The E-SMLC 115 may also communicationwith the base station 103 of assistance data purposes using an LPPaprotocol. The SLP 113 may be responsible for coordination andadministrative functions to provide location services. The SLP 113 mayalso be responsible for positioning functions. The SLP 113 is apositioning node in the user plane.

FIG. 2 illustrates an overview of a positioning measurement performed bya user equipment 101. During the measurement, the user equipment may bein communication with a serving base station 103S. The user equipment101 may be configured to receive measurements from a number of basestations 103A-103C. The user equipment may also be in communication withpositioning nodes E-SMLC 115 and/or SLP 113. During positioningmeasurements, often the bandwidth of the serving cell associated withthe serving base station 103S, the bandwidth of various measured cellsassociated with base stations 103A-103C, and the bandwidth of variousPositioning Reference Signals (PRS) may need to be taken into account.

Limitations of Current Solutions

The following is a discussion on limitations of current solutions whichhave been identified by the inventors. The discussions of thelimitations also comprise a discussion of possible solutions to suchlimitations, which the inventors have realized. During a mobilityprocedure, positioning measurements performed by a user equipment 101may be interrupted or negatively effected. The interruptions and/ornegative effects may be caused by a cell change resulting from themobility procedure.

There are numerous problems associated with current positioningsolutions during a cell change. At least the following problems havebeen identified:

-   -   For positioning measurements, the serving cell may be not in the        OTDOA assistance data and thus the user equipment will not        report measurement for it, so the positioning node is not aware        with the current standard of whether the serving cell has        changed during the measurement period or not, although the        serving cell configuration and the number of changes do impact        the measurement accuracy and reporting time.    -   For measurements with respect to a reference cell (e.g., RSTD        measurements or relative RSRP/RSRQ measurements), the user        equipment behavior and the measurement time is still not clear        when the serving/primary cell changes    -   Theoretically, the user equipment should be able to continue        measurements if they are defined for non-serving cells as well;        however, there may be different impact on the complexity e.g.        depending on whether this is a CA system or whether the        frequency/carrier has changed (since intra- and inter-frequency        requirements are different).    -   If there are multiple cell changes during the measurement, this        may also need to be taken into account.    -   The network node (e.g., positioning node) is not aware of the        serving/primary cell changes which could occur during the        on-going measurement    -   When a measurement is received by the network, the received        measurement may be less accurate and/or reported after a longer        time, but the network may collect statistics on the measurements        and use it for other purposes (e.g., SON) and may wrongly        classify the measurement without being aware of the reason the        degraded performance;    -   When the measurement is being performed, the network being not        aware of the reason for a long measurement time may break the        session before the measurement is received, even though the        measurement time is according to the requirement which may        account for the number of cell switches;    -   When a measurement requirement accounting for the        serving/primary cell changes is tested, the test equipment has        to be aware of e.g. the information associated with cell change;    -   When multiple cell changes occur during a measurement, the        network (e.g., positioning node or SON) would benefit from the        history of cell changes, which currently cannot be reported as a        single measurement and which would be particularly beneficial in        a network deployments with small cells, in particular for        positioning, MDT, user equipment tracking, etc.

Thus, according to some of the example embodiments, a user equipment maybe configured to adapt its behaviour during a positioning measurement asa result of the mobility procedure. Such an adaption may account forcell changes as a result of the mobility procedure. Furthermore, someexample embodiments may be directed towards a network node adaptingpositioning measurement instructions, which may be provided to the userequipment, based on a cell change.

Brief Overview of the Example Embodiments

In order to remedy the above highlighted problems with the current art,example embodiments are presented herein which provide improvedmeasurement management during cell changes. Some of the exampleembodiments may comprise the recordation and use of information,obtained by a user equipment, associated with a current cell. Suchinformation may be utilized by the user equipment, a positioning node, abase station, or any other network node for measurement management orgeneral resource management. Other example embodiments may comprise thealteration of a current measurement scheme based on implemented rulesand/or the user equipment obtained data. Different aspects of theexample embodiments are described in greater detail below according tothe appropriate sub-heading.

Recordation of User Equipment Trajectory

According to some of the example embodiments, a user equipment 101 maybe configured to record data associated with a cell the user equipmentis currently associated with. Example embodiments further comprise theuser equipment retaining such information upon leaving such cell. Thus,the user equipment may retain information associated with a userequipment trajectory and various cell changes.

According to the example embodiments, there are various signallingprocedures and configuration methods for obtaining the informationassociated with the cell change of the user equipment. The informationmay be obtained from the user equipment and/or from a suitable networknode which may serve the user equipment.

The following nodes may be involved in communicating informationassociated with cell changing. It should be appreciated that theexamples provided are non-limiting and are not method steps.

The user equipment may receive (e.g., via LPP or RRC) a request orindication to collect and report the information associated with cellchanging. The information associated with cell changing may becollected, stored and signalled by the user equipment to another node(e.g., positioning node, eNodeB, LMU, MDT node, SON node, etc.).

Radio nodes may also be involved in the communication of informationassociated with cell changes. The radio node may receive (e.g., viaLPPa) a request or indication to collect and report the informationassociated with cell changing. The information associated with cellchanging may be collected, stored and signalled by the radio node toanother node (e.g., another radio node, positioning node, SON node, MDTnode, etc.). The information associated with cell changing may bereceived from the user equipment. The information associated with cellchanging may be received from another radio node (e.g., eNodeB or LMU),e.g., via X2 in a handover command or other signalling.

Various other network nodes may also be involved in the communication ofinformation associated with cell changes. The network node may send arequest or indication to the user equipment to collect and report theinformation associated with cell changing. The network node may send arequest or indication to the radio node to collect and report theinformation associated with cell changing. The network node may send arequest to another network node and receive the information associatedwith cell changing for a specific user equipment or the statistics ofthe information associated with cell changing collected over time and/orfor a group of user equipments.

The information associated with cell changing may be received from auser equipment. The information associated with cell changing may bereceived from another network node (e.g., positioning node, SON node,MDT node, etc.). The information associated with cell changing may alsobe received from a radio node.

The information associated with cell changing may comprise of userequipment trajectory information. The user equipment trajectoryinformation may comprise of at least a list of cell IDs or an orderedsequence of cell IDs of cells on which the user equipment is connectedto or camped on during certain time period. The order of the list may bein order of cell changes over time.

According to some of the example embodiments, all cells over apredetermined time period may be included in the user equipmentrecordation. According to some of the example embodiments, only cells onwhich the user equipment camps on or connects to for at least certainminimum time are provided. According to some of the example embodiments,the list of cells may be obtained over a time period, which isassociated with certain type of measurement, e.g., time over which userequipment performs and logs MDT measurements (e.g., 2 hours typicallyfor MDT). According to some of the example embodiments, the time periodover which cell change information is to be obtained may be linked topositioning measurement session or period (e.g., the time interval ofone RSTD measurement session), etc.

The user equipment may also report an ordered sequence (cell_ID1,cell_ID2, . . . , cell_IDN), where the cells with cell_ID1, cell_ID2, .. . , cell_IDN had been the serving/primary cells during the said timeinterval or one positioning measurement session (e.g. for OTDOA orE-CID). The user equipment may either report the physical cell ID (PCI)or cell global ID (CGI). The user equipment may be configured by thenetwork node to report certain type of cell identifier.

Cells in the list/sequence may also be time-stamped, e.g., together withthe cell identifiers. The time stamped information may be provided indifferent manners. In one example the user equipment may provide thetime for a cell when the user equipment was initially connectedto/camped on to that cell. According to some of the example embodiments,the user equipment may provide the time for a cell when the userequipment was left the serving cell. According to some of the exampleembodiments, the time stamp for a cell may correspond to the time duringwhich user equipment was connected to or camped on to that cell. Theuser equipment may report relative time-stamp for each cell in the list.The relative time may be a time reference to a time provided by thenetwork node or a time-stamp corresponding to the last serving/primarycell or to a reference cell. The user equipment may also be configuredby the network node to report the time-stamp for each serving cellaccording to any of the examples listed above.

The user equipment may also be configured with sets of cell IDs (e.g.first set and second set), which indicate the start and end of thetracking of the trajectory. For example when the serving/primary cellbelongs to first set of cell IDs then the user equipment starts thelogging of the trajectory information and it stops the logging when theserving/primary cell belongs to the second set of cell IDs. The networkcan also configure the time period. For example after the expiry of thistime the user equipment may stop the logging the trajectory informationeven if the no does not find a serving/primary cell whose cell ID doesno match to the second set of cell IDs. Another non-limiting example ofthe first cell IDs may be associated with the first type of cells (e.g.,large or macro cells) and of the second set of cell IDs may beassociated with the second type of cells (e.g., small cells such asfemto or pico cells).

The user equipment may also be configured by the network node to reportat least N (e.g. N=5) neighbour cells of each serving/PCell or specificserving cell/PCell as part of the trajectory information. The userequipment therefore acquires and stores all neighbour cells for thegiven serving cell/PCell and report the results to the network node. Asa special case the user equipment may also be configured by the networknode to report at least the strongest neighbour cell and/or strongestneighbour cell of each serving/PCell or specific serving cell/PCell aspart of the trajectory information.

The user equipment may also be configured to record cell identificationinformation (may be used independently on whether the trajectoryinformation is used in the network or not) for at least one cell in thelist/sequence. Examples of such cell identification may be a lastserving/primary cell during a predetermined time interval, a carrierfrequency of each cell during the predetermined time interval, the firstserving/primary cell during the predetermined time interval, the cellthat has been the serving/primary cell during the longest time withinthe predetermined time interval, the cell(s) selected according to apre-defined rule, the cell(s) on a certain frequency, and/or the cell(s)of a certain type (e.g., CSG cells, macro cells, pico cells).

The user equipment may also be configured to record cell identificationinformation with respect to signal measurements. Specifically, the userequipment may be configured to record signal measurement (e.g. RSRP,RSRQ) results of serving/primary cell. Examples of such measurementsresults may be the smallest and largest values of certain measurementsdone on serving/primary cell while the user equipment is connectedto/camped on this cell, and/or values of the certain measurements doneon serving/primary cell when the user equipment initially connectsto/camps on this cell and/or when user equipment leaves this cell.

According to some of the example embodiments, further examples of cellinformation (relating to measurements) may comprise an indication of acell type for at least one cell in the list/sequence, and/or bandwidthinformation for at least one cell in the list/sequence. Example of suchbandwidth information may comprise a system bandwidth (aka channelbandwidth, cell transmission bandwidth etc), and/or a measurementbandwidth (the bandwidth used for doing specific type(s) ofmeasurement(s)). Some non-limiting examples of such bandwidths are acell measurement bandwidth, specific signal (e.g. PRS) measurementbandwidth, SRS measurement bandwidth, a smallest measurement bandwidthof serving/primary cells (e.g., among all serving/primary cells) duringthe said intervals, a largest measurement bandwidth of serving/primarycells (e.g., among all serving/primary cells) during the said intervals,a smallest system/transmission/channel bandwidth of serving/primarycells (e.g., among all serving/primary cells) during the said intervals,and/or a largest system/transmission/channel bandwidth of allserving/primary cells (e.g., among all serving/primary cells) during thesaid intervals.

According to some example embodiments, the user equipment may also beconfigured to record bandwidth information associated with the entirereported measurement during which at least one cell change occurred.Examples of such information may be a measurement bandwidth based onwhich the measurement reporting time is to be defined (this informationmay be particularly important e.g. for testing measurementrequirements). The user equipment may also be configured to record acell type. Examples of such cell types may be macro, micro, pico, femto,ect.

The user equipment may also be configured to record cell accessinformation. For example, the user equipment may be configured toindicate whether a cell is fully or partially accessible or not to alluser equipments. Examples of such information may be CSG cells, non-CSG,hybrid CSG, any restricted or barred cell, cell barred for specificoperation/services etc, proximity; whether a cell is in proximity of CSGetc., frequency associated with the at least one cell, and/or timinginformation, e.g., SFN, associated with the at least one cell.

According to some of the example embodiments, the information associatedwith cell changing may be provided upon request or when configured(e.g., a configuration message may indicate which elements of the saidinformation are to be provided). According to some example embodiments,the recordation of information may also be mandatory for certainmeasurements (e.g., for MDT measurements, for E-CID, OTDOA, UTDOA orother positioning measurements, for a measurement during which at leastone cell change has occurred, etc.).

It should be appreciated that the user equipment trajectory informationcan be provided by the user equipment in any RRC state e.g. idle state,connected state, low activity states (e.g. CELL_PCH, URA_PCH, CELL_FACHstates etc).

It should also be appreciated that all the examples of recorded cellinformation also be obtained by the user equipment for the neighbourcells associated with each serving/PCell while obtaining the cellchange/trajectory information.

FIG. 3 illustrates an example of a recorded user equipment trajectory.In some example embodiments, the user equipment 101 may be configured tostore the user equipment trajectory information internally, for example,in the form of a cell table 130. As shown, the cell table 130 maycomprise any entries, where each entry may comprise any number offields. In the example provided in FIG. 3, each entry may be timestamped, as described above. Furthermore, the table may comprise anynumber of different entry types. In the example provided in FIG. 3, thecell table 130 comprises a last serving cell ID, a first primary cell,and a longest serving/primary cell ID entry.

It should be appreciated that the use of a cell table is used merely forexplanation and any other form of recordation or listing may beutilized. Furthermore, the recordation techniques described above arealso presented as examples. Any form of cell related information may berecorded and used for the management of radio resources.

User Equipment Behaviour During a Serving Cell/Primary Cell Change

According to some of the example embodiments,

A user equipment upon receiving a measurement configuration or schememay take appropriate actions while taking into account the cell changeduring a measurement interval or during a configured interval. The cellchange may occur due to various reasons e.g. handover, cell reselection,RRC re-establishment, RRC connection release with redirection to atarget cell, PCell switching (aka PCell change or primary serving cellchange) etc.

A few non-limiting examples are herein provided to illustrate the userequipment behaviour during serving cell/primary cell changes over acertain time period e.g. measurement period of OTDOA RSTD measurements,according to some of the example embodiments.

The OTDOA session can be of several seconds and thus HO can occur duringthe session. Without these requirements the OTDOA session can be aborteddue to HO. This would require the positioning node to initiate a newsession leading to wastage of previous measurements and leading to muchlonger overall delay. The problem becomes even more severe in an areawith many small cells where the HW probability is high.

User Equipment Behaviour Under HO when Intra-Frequency RSTD is Measured:

Consider the first example in which the user equipment is connected toits serving cell and it is configured by the positioning node to performOTDOA intra-frequency and/or inter-frequency measurements. The userequipment may receive the OTDOA assistance data for performing RSTDmeasurements on cells which are in the assistance data. While the userequipment performs the RSTD measurements, the serving cell of the userequipment may change (e.g. due to HO). As an example the serving cellmay change K times during a time period. All the K serving cells duringthe time period may not have the same system bandwidth. For example somecells have smaller BW (e.g. 15 RB) whereas others may have BW equal to50 RB. The Positioning Reference Signal (PRS) BW of the cells in theOTDOA can be larger than, smaller than, or equal to the BW of theserving cells. For example assume PRS BW of all cells is 50 RBs. Whenthe user equipment serving cell BW is greater than or equal to that ofthe PRS BW then the UE can measure RSTD on the entire PRS BW of thecell. Otherwise when the serving cell BW is smaller than the PRS BW thenthe UE can at most measure on the PRS BW equal to the serving cell BW.

Thus, according to some of the example embodiments, the following rulesmay be implemented, for example, when the user equipment performs RSTDmeasurements and the HO occurs. The examples may be applicable to bothFDD and TDD.

Rules for an Intra-Frequency RSTD Measurement Period:

If the intra-frequency handover occurs while intra-frequency RSTDmeasurements are being performed, the user equipment may complete theon-going OTDOA measurement session. However, in this case (i.e. whenhandover occurs) the RSTD measurement period over which the userequipment performs RSTD of cells which are in the assistance data may belonger than usual. This usual means when there is no handover. Thereason is that the user equipment may not be able to measure the RSTDwhen user equipment is doing handover. Another reason is that the PRSsignals over which the user equipment measures RSTD may collide oroverlap (i.e. fully or partially) with the time instance when handoveroccurs. Another implicating factor is the bandwidth of the serving cell.It should also be noted that more than one handover may occur over theRSTD measurement period.

Hence as an example, the RSTD measurement period(T_(RSTDIntraFreq,E-UTRAN,HO)) can be expressed according to thefollowing general expression as a function of the following parameters:T_(RSTDIntraFreq,E-UTRAN,HO)=f(T_(RSTDIntraFreq,E-UTRAN),K,T_(PRS),T_(HO),. . . ). One specific non-limiting example may be:

T_(RSTDIntraFreq,E-UTRAN,HO)=T_(RSTDIntraFreq,E-UTRAN)+K×(T_(PRS)+T_(HO))ms, K is the number of times the intra-frequency handover occurs duringT_(RSTDIntraFreq,E-UTRAN,HO), T_(PRS) is the cell-specific positioningsub-frame configuration period e.g. 1024 ms,T_(RSTDIntraFreq,E-UTRAN,HO) is the time for doing intra-frequency RSTDmeasurements if no HO occurs, and T_(HO) is the time during which theintra-frequency RSTD measurement may not be possible due tointra-frequency handover; it can be up to 45 ms.

Rules for Intra-Frequency RSTD Accuracy:

Another Aspect of the User Equipment Behaviour as Indicated Above isRelated to the serving cell BW while the user equipment performs theRSTD measurement on cells. If the user equipment traverses more than oneserving cell (i.e. served by 2 or more cells) over the RSTD measurementperiod, then the serving cell BW may affect the accuracy of the RSTDmeasurements. The RSTD measurement accuracy is typically expressed in abasic time unit (Ts), e.g. in the order of +/−100 ns. The accuracydepends on factors such as PRS BW, number of PRS sub-frames etc. Theserving cell BW may affect the bandwidth over which the user equipmentcan measure the RSTD, which is done on PRS, of the measured cell.

Therefore, as a general rule it may be pre-defined that if the userequipment is performing an RSTD measurement while the handover occursthen the user equipment may meet the RSTD measurement accuracy by takinginto consideration at least the bandwidth (i.e.channel/system/transmission BW) of all its serving cells over the RSTDmeasurement period. According to another general rule it may bepre-defined that if the user equipment is doing RSTD measurement whilethe handover occurs then the user equipment may meet the RSTDmeasurement accuracy by taking into consideration at least the bandwidth(i.e. channel/system BW) of all its serving cells over the RSTDmeasurement period as well as the PRS BW of the measured cells.

More specifically, it may be pre-defined that the user equipment meetsthe RSTD measurement accuracy corresponding to the PRS bandwidth whichis not larger than the minimum channel/system/transmission bandwidth ofall the serving cells during the RSTD measurement(T_(RSTDIntraFreq,E-UTRAN,HO)).

User Equipment Behaviour Under HO when Inter-Frequency RSTD is Measuredand Rules for Inter-Frequency RSTD Measurement Period:

The user equipment behavior when inter-frequency or intra-frequency HOoccurs while the user equipment does inter-frequency RSTD measurementsis very similar to the user equipment behavior in case ofintra-frequency HO when user equipment does intra-frequency HO (asexplained above). For example, the inter-frequency RSTD delay can belonger than the usual inter-frequency RSTD delay. More specifically, theRSTD measurement period (T_(RSTDInterFreqTDD,E-UTRAN,HO)) can beaccording to the following expression:T_(RSTDInterFreqTDD,E-UTRAN,HO)=T_(RSTDInterFreqTDD,E-UTRAN)+K×(T_(PRS)+T_(HO))ms, where: K is the number of times the inter-frequency or/andintra-frequency handover occurs during T_(RSTDInterFreqTDD,E-UTRAN,HO),T_(HO) is the time during which the inter-frequency RSTD measurement maynot be possible due to inter-frequency handover; it can be up to 45 ms.

The inter-frequency measurements may be performed in gaps, which may bereconfigured if the HO occurs e.g. by new serving cell. Thereforeadditional delay due to gap reconfiguration may be needed e.g.T _(RSTDInterFreqTDD,E-UTRAN,HO) =T _(RSTDInterFreqTDD,E-UTRAN) +K×(T_(PRS) +T _(HO) +T _(gap-config)) mswhereT_(gap-config) is the time to configure or reconfigure gaps forinter-frequency measurements; it can be up to 50 ms.

Rules for Inter-Frequency RSTD Accuracy:

Similarly, the RSTD measurement accuracy may be affected by the servingcell BW. For example, if the inter-frequency over which the userequipment does RSTD measurements becomes intra-frequency then servingcell BW may affect the RSTD accuracy. Similarly, if the user equipmentdoes not need gaps for measuring the inter-frequency over which the userequipment does RSTD measurements, then serving cell BW may affect theRSTD accuracy. Similarly, if the reference cell is on the servingcarrier then the serving cell BW may affect the RSTD accuracy.

Therefore, as a general rule it may also be pre-defined that if the userequipment is doing inter-frequency RSTD measurement while theinter-frequency or intra-frequency handover occurs then the userequipment may meet the RSTD measurement accuracy by taking intoconsideration at least the bandwidth (i.e. channel/system/transmissionBW) of all its serving cells over the RSTD measurement period.

According, to another general rule it may be pre-defined that if theuser equipment is doing inter-frequency RSTD measurement while theinter-frequency or intra-frequency handover occurs, then the userequipment meets the RSTD measurement accuracy by taking intoconsideration at least the bandwidth (i.e. channel/system BW) of all itsserving cells over the RSTD measurement period as well as the PRS BW ofthe measured cells. More specifically it may be pre-defined that theuser equipment meets the RSTD measurement accuracy corresponding to thePRS bandwidth which is not larger than the minimumchannel/system/transmission bandwidth of all the serving cells duringthe inter-frequency RSTD measurement.

User Equipment Behaviour Under Primary Cell Change when RSTD isMeasured:

If the user equipment is configured in carrier aggregation (e.g. atleast with one secondary cell) and the primary cell is changed whileuser equipment is doing the RSTD measurements then the user equipmentbehaviour may also be defined. The behaviour in terms of RSTDmeasurement period and accuracy are very similar to that in case of HOas explained below with an example.

Rules for RSTD Measurement Period Under PCell Change in CA:

If the PCell is changed regardless whether the primary component carrieris changed or not while the RSTD measurements are being performed oncells belonging the primary component carrier (PCC) or the secondarycomponent (SCC) carrier or on primary as well as on secondary componentcarriers then the user equipment completes the on-going OTDOAmeasurement session. The user equipment may also meet the OTDOAmeasurement and accuracy requirements for the primary or secondarycomponent carrier or all carriers depending whether cells are measuredon PCC, SCC or on both PCC and SCC. The total RSTD measurement period(T_(RSTD,E-UTRAN,Pcell) _(_) _(charge)) can be according to thefollowing expression: T_(RSTD,E-UTRAN,Pcell) _(_)_(charge)=T_(RSTD,E-UTRAN)+K×(T_(PRS)+T_(Pcell) _(_) _(charge)) ms whereK is the number of times the PCell is changed duringT_(RSTD,E-UTRAN,Pcell) _(_) _(charge), T_(Pcell) _(_) _(charge) is thetime during which the RSTD measurement may not be possible due to PCellchange; it can be up to ms, and T_(RSTD,E-UTRAN) corresponds to theE-UTRAN intra-frequency RSTD measurement period.

Rules for RSTD Measurement Accuracy Under PCell Change in CA:

The RSTD measurement accuracy may also depend upon the BW of all thePCell(s) during the RSTD measurement period. For example as a generalrule it may be pre-defined that if the PCell is changed (regardlesswhether the primary carrier changes or not) while the user equipment isdoing RSTD measurement when configured with at least one secondary cell(SCell) then the user equipment may meet the RSTD measurement accuracyby taking into consideration at least the bandwidth (i.e.channel/system/transmission BW) of all its PCell(s) over the RSTDmeasurement period. According to another general rule it may bepre-defined that if the user equipment is doing RSTD measurement whilethe PCell changes then the user equipment meets the RSTD measurementaccuracy by taking into consideration at least the bandwidth (i.e.channel/system BW) of all its PCell(s) over the RSTD measurement periodas well as the PRS BW of the measured cells.

More specifically, it may be pre-defined that the user equipment meetsthe RSTD measurement accuracy corresponding to the PRS bandwidth whichis not larger than the minimum channel/system/transmission bandwidth ofall the PCells during the RSTD measurement when configured with at leastone SCell.

It should be appreciated that the modification or user equipmentbehaviour and/or a current measurement scheme may be based on the aboveidentified rules and/or cell information which is recorded and stored bythe user equipment, as described under the previous heading entitled‘Recordation of user equipment trajectory’.

Using the Information Associated with the Cell Change

The information associated with cell changing may be collected, storedand used by different nodes for different purposes, e.g., measurement orgeneral resource management. Non-limiting examples of nodes which mayobtain the cell change information of the user equipment or of wirelessterminal or of a mobile relay are:

-   -   Radio network node e.g., eNode B, radio network controller, base        station, relay node, donor node serving relay, mobile relay node        etc.    -   Positioning node e.g. E-SMLC in LTE    -   Network nodes in general e.g. MDT node, SON node, core network        node (e.g. MME in LTE), OSS node, O&M node, network management        and planning node etc.    -   Test equipment nodes/system simulator e.g. obtaining information        during a test to verify that the user equipment or wireless        terminal or of mobile relay are compliant to the pre-defined        rule, signalling and requirements associated with the cell        change of the user equipment.

The above nodes may collect the information associated with cellchanging for different user equipments and create statistics, forexample, over time and/or for a specific group of user equipments. Ingeneral the acquired cell change information can be used by theacquiring node for the ‘monitoring, planning and management’ of thenetwork. More specifically the above nodes may use theresults/statistics for one or more of the following tasks or functionswhich are provided as a non-limiting example:

-   -   Positioning (e.g., enhancing RFPM, pattern matching or AECID),    -   UE tracking e.g. to know the typical UE path or subscriber        travel route,    -   SON; automated tuning of network parameters, addition of new        cells/removal of existing cells, upgrading of existing cells        (e.g. extending cell BW or PRS BW etc),    -   MDT; planning of network in general such as installation of new        BS sites, update of cell type (e.g. increase or decrease of BS        max output power) etc.,    -   HO optimization; improve parameters related to the handover e.g.        HO margin, time to trigger,    -   CA configuration optimization.        Applicability to Test Case and Test Equipment

User equipment configuration (or any wireless device e.g. mobile relay)may also be configured in the test equipment (TE) node (aka systemsimulator (SS)). The TE or SS may implement all configuration methodsrelated to cell change in order to be able to configure the userequipment for testing. The purpose of testing is to verify that the userequipment is compliant to the pre-defined rules, protocols, signallingand/or requirements associated with the cell change feature e.g.tracking and logging of the user equipment trajectory during the cellchange.

The TE or SS will also be capable of:

-   -   Receiving the UE measurement results associated with the cell        change    -   Analysing the received results e.g. comparing the with the        reference results. The reference can be based on the pre-defined        requirements or UE behaviour.

Example User Equipment Configuration

FIG. 4 illustrates an example of a user equipment node 101, according tosome of the example embodiments. The user equipment 101 may comprise anynumber of communication ports, for example a receiving port 307 and atransmitting port 308. The communication ports may be configured toreceive and transmit any form of communications data 303 and 305,respectively. It should be appreciated that the user equipment 101 mayalternatively comprise a single transceiver port. It should further beappreciated that the communication or transceiver port may be in theform of any input/output communications port known in the art.

The user equipment 101 may further comprise at least one memory unit 309that may be in communication with the communication ports 307 and/or308. The memory unit 309 may be configured to store received,transmitted, and/or measured data of any kind and/or executable programinstructions. The memory unit 309 be any suitable type of computerreadable memory and may be of a volatile and/or non-volatile type.

The user equipment 101 may also comprise a measurement unit 313 whichmay be configured to perform measurements. The user equipment 101 mayfurther comprise an alteration unit 315 that may be configured to alteraspects of measurements performed by the user equipment (e.g., aduration of measurement time and/or a measurement bandwidth). The userequipment 101 may further comprise a general processing unit 311.

It should be appreciated that the measurement unit 313, alteration unit315, and/or the processing unit 311 may be any suitable type ofcomputation unit, e.g. a microprocessor, digital signal processor (DSP),field programmable gate array (FPGA), or application specific integratedcircuit (ASIC), or any form of processing circuitry. It should also beappreciated that the measurement unit 313, alteration unit 315, and/orthe processing unit 311 need not be comprised as separate units. Themeasurement unit 313, alteration unit 315, and/or the processing unit311 may be comprised as a single computational unit or any number ofunits. It should also be appreciated that the user equipment 101 may bea mobile phone, a Personal Digital Assistant (PDA), or any other LTEnetwork unit capable to communicate with a base station over a radiochannel.

Example Network Node Configuration

FIG. 5 provides an illustrative example of a network node configuration,according to some of the example embodiments. In some exampleembodiments, the network node may be a radio base station 103, an E-SMLCnode 115, or a SLP node 113.

The network node may comprise any number of communication ports, forexample a receiving port 207 and a transmitting port 208. Thecommunication ports may be configured to receive and transmit any formof communications data 203 and 205, respectively. It should beappreciated that the network node may alternatively comprise a singletransceiver port. It should further be appreciated that thecommunication or transceiver port may be in the form of any input/outputcommunications port known in the art.

The network node may further comprise at least one memory unit 209 thatmay be in communication with the communication ports 207 and/or 208. Thememory unit 209 may be configured to store received, transmitted, and/ormeasured data of any kind and/or executable program instructions. Thememory unit 209 be any suitable type of computer readable memory and maybe of a volatile and/or non-volatile type.

The network node may also comprise an alteration unit 213 that may beconfigured to determine instructions for altering aspects of a userequipment measurement (e.g., altering a duration of measurement timeand/or a measurement bandwidth). The alteration unit 213 may also beconfigured to provide a user equipment with information relating to acell change. The network node may further comprise a general processingunit 311.

It should be appreciated that the alteration unit 213 and/or theprocessing unit 211 may be any suitable type of computation unit, e.g. amicroprocessor, digital signal processor (DSP), field programmable gatearray (FPGA), or application specific integrated circuit (ASIC). Itshould also be appreciated that the alteration unit 213 and/or theprocessing unit 211 need not be comprised as separate units. Thealteration unit 213 and/or the processing unit 211 may be comprised as asingle computational unit or any number of units.

Example User Equipment Operations

FIG. 6 illustrates example operations which may be performed by the userequipment 101 of FIG. 3, according to some of the example embodiments.The example operations are directed towards the handling of a cellchange. A cell change refers to a user equipment 101 changing the cellof which the user equipment is currently situated, e.g., a cell changefrom a first or current cell to a second cell. It should be appreciatedthat the network node may be a base station 103, a E-SMLC node 115, of aSLP node 113.

Operation 41

The user equipment 101 is configured to perform 41 at least onemeasurement. The measurement unit 313 is configured to perform the atleast one measurement. According to some of the example embodiments, theat least one measurement may be a RSTD measurement for OTDOApositioning, a RSRP, a RSRQ, and/or a user equipment Rx-Tx timedifference measurement.

Operation 43

The user equipment 101 is further configured to receive 43, from anetwork node, a notification of, and information associated with, a cellchange from a first cell to a second cell. The receiving port 307 isconfigured to receive the notification of, and the informationassociated with, the cell change.

According to some example embodiments, the cell change may be a servingcell change, a serving cell set change, an active cell set change, aPCell change on a same frequency carrier, or a cell change due tocarrier switching. According to some of the example embodiments, thecell change may be a result of any one of a handover procedure; cellreselection; Radio Resource Control, RRC, connection re-establishment;RRC connection release with redirection to a target cell; primary cell,PCell, change on same frequency as primary component carrier, PCC, in amulti-carrier system; PCell change due to change of PCC in amulti-carrier system; serving cell set change in a multi-carrier system,or active cell set change in a multi-carrier system. According to someof the example embodiments, the first cell may be a serving cell duringa first period, and the second cell may be a serving cell during asecond period, where the second period occurs after the first period intime.

According to some example embodiments, the received informationassociated with the cell change may comprise a type of measurement to beperformed, a type of cell identification for reporting and/or bandwidthinformation. According to some of the example embodiments, the receivednotification and/or received information associated with the cell changeis received upon request and/or is received periodically based on aconfiguration which may be programmable.

Operation 45

The user equipment is also configured to perform 45 the cell changeduring the at least one measurement. The measurement unit 313 isconfigured to perform the cell change during the at least onemeasurement.

Operation 47

The user equipment is also configured to alter 47 a duration of ameasurement time over which the at least one measurement is performed.The alteration unit 315 is configured to alter the duration of themeasurement time over which the at least one measurement is performed.

It should be appreciated that the alteration 47 may be performed basedon rules associated with the user equipment. For example, the rulesassociated with the user equipment may be pre-defined rules which areprovided within the user equipment. It should be further appreciatedthat such rules may be adjustable or user programmable. Furthermore, itshould be appreciated that such rules may also be provided by thenetwork node along with the information associated with the cell changeand/or the received notification.

Operation 49

The user equipment is also configured to alter 49 a measurementbandwidth of the at least one measurement, wherein the altering is basedon associated bandwidths of the first and second cells. The alterationunit 315 is configured to alter the measurement bandwidth of the atleast one measurement, wherein the altering is based on associatedbandwidths of the first and second cells.

It should be appreciated that the alteration 49 may be performed basedon rules associated with the user equipment. For example, the rulesassociated with the user equipment may be pre-defined rules which areprovided within the user equipment. It should be further appreciatedthat such rules may be adjustable or user programmable. Furthermore, itshould be appreciated that such rules may also be provided by thenetwork node along with the information associated with the cell changeand/or the received notification.

Example Operation 55

According to some of the example embodiments, the altering 49 mayfurther comprise altering 55 the measurement bandwidth to at least oneof a minimum of bandwidths of the first and second cells, and/or abandwidth which is not larger than bandwidths of the first and secondcells. The alteration unit 315 may be configured to alter themeasurement bandwidth to at least one of a minimum of bandwidths of thefirst and second cells, and/or a bandwidth which is not larger thanbandwidths of the first and second cells.

According to some of the example embodiments, the bandwidth of the firstor second cell may be the channel bandwidth or a transmission bandwidth.According to some of the example embodiments, the measurement bandwidthmay be the bandwidth of reference signals to be measured. According tosome of the example embodiments, the reference signals may bePositioning Reference Signals (PRS) and the measurement bandwidth may bea PRS bandwidth.

Operation 57

The user equipment is also configured to complete 57 the at least onemeasurement based on the altered duration of measurement time and thealtered measurement bandwidth. The measurement unit 313 may beconfigured to complete the at least one measurement based on the alteredduration of measurement time and the altered measurement bandwidth.

Example Operation 61

According to some of the example embodiments, the user equipment may beconfigured to time stamp 61 results of the at least one measurement. Themeasurement unit 313 may be configured to time stamp the results of theat least one measurement.

Example Operation 63

According to some of the example embodiments, the user equipment may beconfigured to store 63 compiled information associated with the cellchange of the first cell to the second cell, where the compiledinformation is provided by the user equipment. The memory unit 309 maybe configured to store the compiled information associated with the cellchange of the first cell to the second cell, where the compiledinformation is provided by the user equipment.

According to some of the example embodiments, the compiled informationassociated with the change of the first cell to the second cell maycomprise user equipment trajectory information. The user equipmenttrajectory data may comprise an ordered or non-ordered list of cellidentities of cells which the user equipment is connected to and/orcamped during a period of time, and/or cell information. The cellinformation may comprise a carrier frequency of each serving cell,system bandwidth, measurement bandwidth and/or a cell type.

Example Operation 65

According to some of the example embodiments, the user equipment may beconfigured to send 65 the compiled information to a network node oranother user equipment. The transmitting port 308 may be configured tosend the compiled information to the network node or another userequipment.

Example Operation 67

According to some of the example embodiments, the user equipment may beconfigured to adjust 67 a measurement accuracy of the at least onemeasurement with respect to the altered duration of measurement time andthe altered measurement bandwidth. The alteration unit 315 may beconfigured to adjust the measurement accuracy of the at least onemeasurement with respect to the altered duration of measurement time andthe altered measurement bandwidth.

Example Network Node Operations

FIG. 7 illustrates example operations which may be performed by thenetwork node of FIG. 4, according to some of the example embodiments.The example operations are directed towards handling a cell change for auser equipment. A cell change refers to a user equipment 101 changingthe cell of which the user equipment is currently situated, e.g., a cellchange from a first or current cell to a second cell. It should beappreciated that the network node may be a base station 103, a E-SMLCnode 115, of a SLP node 113.

Operation 71

The network node is configured to send 71, to a user equipment, arequest to perform at least one measurement. The transmitting port 208is configured to configured to send, to the user equipment, the requestto perform at least one measurement.

According to some of the example embodiments, the at least onemeasurement may be a RSTD measurement for OTDOA positioning, a RSRP, aRSRQ, and/or a user equipment Rx-Tx time difference measurement.

Operation 73

The network node is also configured to determine 73 informationassociated with a cell change from a first cell to a second cell. Theinformation associated with the cell change comprises alterationinstructions for altering a user equipment measurement time andmeasurement bandwidth in a presence of the cell change. The alterationunit 213 is configured to determine the information associated with thecell change from the first cell to the second cell.

According to some example embodiments, the cell change may be a servingcell change, a serving cell set change, an active cell set change, aPCell change on a same frequency carrier, or a cell change due tocarrier switching. According to some of the example embodiments, thecell change may be a result of any one of a handover procedure; cellreselection; Radio Resource Control, RRC, connection re-establishment;RRC connection release with redirection to a target cell; primary cell,PCell, change on same frequency as primary component carrier, PCC, in amulti-carrier system; PCell change due to change of PCC in amulti-carrier system; serving cell set change in a multi-carrier system,or active cell set change in a multi-carrier system. According to someof the example embodiments, the first cell may be a serving cell duringa first period, and the second cell may be a serving cell during asecond period, where the second period occurs after the first period intime.

Operation 75

The network node is also configured to send 75, to the user equipment, anotification of, and information associated with, the cell change. Theinformation associated with the cell change comprises instructions foraltering. The transmitting port 208 is configured to send, to the userequipment, the notification of, and the information associated with, thecell change.

According to some of the example embodiments, the instructions foraltering may comprise instructions for determining the alteredmeasurement time and/or the altered measurement bandwidth, and theinstructions for altering may be based on predetermined rules. Accordingto some of the example embodiments, the instructions for altering maycomprise instructions for altering a measurement bandwidth to at leastone of a minimum of bandwidths of the first and second cells, and/or abandwidth which is not larger than the bandwidths of the first andsecond cells. In some example embodiments, the bandwidth of the first orsecond cell is the channel bandwidth or the transmission bandwidth. Insome example embodiments, the measurement bandwidth is the bandwidth ofreference signals to be measured. In some example embodiments, thereference signals are Positioning Reference Signals (PRS) and themeasurement bandwidth is a PRS bandwidth.

Operation 81

The network node is also configured to receive 81, from the userequipment, measurement data, where the measurement data comprises atleast one other measurement performed over the altered duration ofmeasurement time and the altered measurement bandwidth. The alteredduration of measurement time and the altered measurement bandwidth arebased on bandwidths associated with the first and second cells. Thereceiving port 207 is configured to receive, from the user equipment,the measurement data.

Example Operation 83

According to some of the example embodiments, the network node may beconfigured to send 83 altered measurement instructions based on receivedmeasurement data. The transmitting port 208 may be configured to sendthe altered measurement instructions based on the received measurementdata.

According to some of the example embodiments, the altered measurementinstructions may comprise instructions for adjusting a measurementaccuracy of the at least one measurement with respect to the alteredduration of the measurement time and the altered measurement bandwidth.

CONCLUSION

The embodiments described herein are not limited to a specificmeasurement, unless clearly stated. The signalling described in theexample embodiments is either via direct links (protocols or physicalchannels) or logical links (e.g. via higher layer protocols and/or viaone or more network nodes). For example, in LTE in the case ofsignalling between E-SMLC and LCS Client the positioning result may betransferred via multiple nodes (at least via MME and/or GMLC).

Although the description is mainly given for a user equipment it shouldbe understood by the skilled in the art that “user equipment” is anon-limiting term which means any wireless device or node typicallycapable of receiving in DL and transmitting in UL (e.g. PDA, laptop,mobile, sensor, fixed relay, mobile relay or even a radio base station,e.g. femto base station). The example embodiments may apply for non-CAUE or both for user equipments capable and not capable of performinginter-frequency measurements without gaps, e.g. also including userequipments capable of carrier aggregation.

Positioning node described in different embodiments is a node withpositioning functionality. For example, for LTE it may be understood asa positioning platform in the user plane (e.g., SLP in LTE) or apositioning node in the control plane (e.g., E-SMLC in LTE). SLP mayalso consist of SLC and SPC, where SPC may also have a proprietaryinterface with E-SMLC. In a testing environment, at least positioningnode may be simulated or emulated by test equipment.

A cell is associated with a radio node, where a radio node or radionetwork node or eNodeB used interchangeably in the example embodimentdescription, comprises in a general sense any node transmitting radiosignals used for measurements, e.g., eNodeB, macro/micro/pico basestation, home eNodeB, relay, beacon device, or repeater. A radio nodeherein may comprise a radio node operating in one or more frequencies orfrequency bands. It may be a radio node capable of CA. It may also be asingle- or multi-RAT node. A multi-RAT node may comprise a node withco-located RATs or supporting multi-standard radio (MSR) or a mixedradio node.

A coordinating node coordinating other network or radio network nodesand/or receiving/transmitting the information or coordination messagesassociated with cell change may be present in the network. Example nodesthat may take the coordinating node role, at least in part, are SONnode, MDT node, positioning node, O&M node, etc.

The example embodiments are not limited to LTE, but may apply with anyRAN, single- or multi-RAT. Some other RAT examples are LTE-Advanced,UMTS, HSPA, GSM, CDMA2000, HRPD, WiMAX, and WiFi.

The foregoing description of the example embodiments have been presentedfor purposes of illustration and description. The foregoing descriptionis not intended to be exhaustive or to limit example embodiments to theprecise form disclosed, and modifications and variations are possible inlight of the above teachings or may be acquired from practice of variousalternatives to the provided embodiments. The examples discussed hereinwere chosen and described in order to explain the principles and thenature of various example embodiments and its practical application toenable one skilled in the art to utilize the example embodiments invarious manners and with various modifications as are suited to theparticular use contemplated. The features of the embodiments describedherein may be combined in all possible combinations of methods,apparatus, modules, systems, and computer program products. It should beappreciated that any of the example embodiments presented herein may beused in conjunction, or in any combination, with one another.

It should be noted that the word “comprising” does not necessarilyexclude the presence of other elements or steps than those listed andthe words “a” or “an” preceding an element do not exclude the presenceof a plurality of such elements. It should further be noted that anyreference signs do not limit the scope of the claims, that the exampleembodiments may be implemented at least in part by means of bothhardware and software, and that several “means”, “units” or “devices”may be represented by the same item of hardware.

Some example embodiments may comprise a portable or non-portabletelephone, media player, Personal Communications System (PCS) terminal,Personal Data Assistant (PDA), laptop computer, palmtop receiver,camera, television, and/or any appliance that comprises a transducerdesigned to transmit and/or receive radio, television, microwave,telephone and/or radar signals.

The various example embodiments described herein are described in thegeneral context of method steps or processes, which may be implementedin one aspect by a computer program product, embodied in acomputer-readable medium, including computer-executable instructions,such as program code, and executed by computers in networkedenvironments. A computer-readable medium may include removable andnon-removable storage devices including, but not limited to, Read OnlyMemory (ROM), Random Access Memory (RAM), compact discs (CDs), digitalversatile discs (DVD), etc. Generally, program modules may includeroutines, programs, objects, components, data structures, etc. thatperform particular tasks or implement particular abstract data types.Computer-executable instructions, associated data structures, andprogram modules represent examples of program code for executing stepsof the methods disclosed herein. The particular sequence of suchexecutable instructions or associated data structures representsexamples of corresponding acts for implementing the functions describedin such steps or processes.

In the drawings and specification, there have been disclosed exemplaryembodiments. However, many variations and modifications can be made tothese embodiments. Furthermore, it should be appreciated that theexample embodiments presented herein may be used in any combination withone another. Accordingly, although specific terms are employed, they areused in a generic and descriptive sense only and not for purposes oflimitation, the scope of the embodiments being defined by the followingclaims.

The invention claimed is:
 1. A method in a user equipment for handling acell change, the method comprising: performing at least one measurement;performing the cell change during the at least one measurement;determining a duration of a measurement time over which the said atleast one measurement is performed; completing the at least onemeasurement based on the determined duration of measurement time.
 2. Themethod of claim 1, wherein the cell change of the first cell to thesecond cell is a result of any of a handover procedure, cellreselection, Radio Resource Control, RRC, connection re-establishment,RRC connection release with redirection to a target cell, primary cell,PCell, change on same frequency as primary component carrier, PCC, in amulti-carrier system, PCell change due to change of PCC in amulti-carrier system, serving cell set change in a multi-carrier system,or active cell set change in a multi-carrier system.
 3. The method ofclaim 1, wherein the first cell is a serving cell during a first period,and the second cell is a serving cell during a second period, whereinthe second period occurs after the first period in time.
 4. The methodof claim 1, wherein the user equipment receives information associatedwith the cell change, the received information comprising any one or acombination of: a type of measurement to be performed, a type of cellidentification for reporting, and bandwidth information.
 5. The methodof claim 1, further comprising storing compiled information associatedwith the cell change of the first cell to the second cell, said compiledinformation being provided by the user equipment.
 6. The method of claim5, wherein the compiled information associated with the change of thefirst cell to the second cell comprises user equipment trajectoryinformation, said user equipment trajectory data comprising an orderedor non-ordered list of cell identities of cells which the user equipmentis connected to and/or camped during a period of time, and/or cellinformation, said cell information comprising a carrier frequency ofeach serving cell, system bandwidth, measurement bandwidth and/or a celltype.
 7. The method of claim 5, further comprising sending the compiledinformation to a network node or another user equipment.
 8. The methodof claim 1, wherein the user equipment receives a notification and/orinformation associated with the cell change upon request and/orperiodically based on a configuration.
 9. The method of claim 1, whereinthe completing further comprises utilizing received informationassociated with the cell change in the at least one measurement as theat least one measurement is on-going.
 10. The method of claim 1, whereinperforming and/or the completing the at least one measurement furthercomprises timing stamping results of the at least one measurement.
 11. Auser equipment for handling a cell change, the user equipmentcomprising: a memory; and a processing circuitry coupled to the memory,wherein the processing circuitry is configured to perform at least onemeasurement; perform the cell change during the at least onemeasurement; determine a duration of a measurement time over which thesaid at least one measurement is performed; and complete the at leastone measurement based on the determined duration of measurement time.12. The user equipment of claim 11, wherein the cell change of the firstcell to the second cell is a result of any of a handover procedure, cellreselection, Radio Resource Control, RRC, connection re-establishment,RRC connection release with redirection to a target cell, primary cell,PCell, change on same frequency as primary component carrier, PCC, in amulti-carrier system, PCell change due to change of PCC in amulti-carrier system, serving cell set change in a multi-carrier system,or active cell set change in a multi-carrier system.
 13. The userequipment of claim 11, wherein the first cell is a serving cell during afirst period, and the second cell is a serving cell during a secondperiod, wherein the second period occurs after the first period in time.14. The user equipment of claim 11, further comprising: a receive portconfigured to receive information associated with the cell change,wherein the information comprises any one or a combination of a type ofmeasurement to perform, a type of cell identification for reporting, andbandwidth information.
 15. The user equipment of claim 11, furthercomprising a memory configured to store compiled information associatedwith the cell change of the first cell to the second cell.
 16. The userequipment of claim 15, wherein the compiled information associated withthe change of the first cell to the second cell comprises user equipmenttrajectory information, said user equipment trajectory data comprisingan ordered or non-ordered list of cell identities of cells which theuser equipment is connected to and/or camped during a period of time,and/or cell information, said cell information comprising a carrierfrequency of each serving cell, system bandwidth, measurement bandwidthand/or a cell type.
 17. The user equipment of claim 15, furthercomprising a transmitting port configured to send the compiledinformation to a network node or another user equipment.
 18. The userequipment of claim 11, further comprising: a receive port configured toreceive a notification and/or information associated with the cellchange upon request and/or periodically based on a configuration. 19.The user equipment of claim 11, further comprising: a receive portconfigured to receive information, wherein the processing circuitry isfurther configured to utilize the received information associated withthe cell change in the completion of the at least one measurement, whilesaid at least one measurement is on-going.
 20. The user equipment ofclaim 11, wherein processing circuitry is further configured to timestamp results of the at least one measurement.